Friction modified oil

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Sep 4, 2003
Central Arkansas
What is a friction modified oil? Does moly or boron make it modified. And is a friction modified oil better than one with a lot of zinc and phos (HDMO)? I know it has been asked before, but it seems as though the term friction modified is a catch phrase.
EP additives, Friction modifiers and anti-wear additives all improve friction to some degree. Oils like Mobil 1 use Boron and Molybdenum as their FM. Redline uses a lot of Moly as both an AW additive and FM along with ZDP which can aid in FM. Oils like Delvac 1, AFL, or Deisel oils usually contain higher levels of ZDP, no Moly and a little boron. So when your comparing oils like Delvac 1/Amsoil AFL to Mobil 1/Amsoil ASL/ATM for example, they won't be as friction modified for gas engines. Not all engines need a highly friction modified oil. Redline's POE base oil alone has a lower Cf then a PAO or any other base oil. Amsoil uses things that don't show up in VOA's. This is especially true for their S2k 0w-30 oil. Molekule has an excellent post in this topic: HERE [ April 11, 2004, 06:40 PM: Message edited by: buster ]
KW, With respect to engine oils and Gear Lubes, friction modified means an additive that reduces oil and mechanical friction. With respect to transmissions and LSD's, it means a chemical added to the the fluid to change the frictional characteristics for specific purposes, such as in different types of automatic transmission fluids. But here we use, "Friction-Modified" with a hyphen. Boron is a secondary antiwear add with ZDDP being the primary AW add. Moly (as in MoTDC) in concentrations of 50 ppm to 600 ppm, act as friction reducers. Another friction reducer is nonmetallo-organic esters and metallo-organic esters. Organic esters have been used as friction Reducers in engine oils for many years, we just called them sperm-whale oils, lards, fatty acid oils, etc. See also:;f=4;t=000315 [ April 11, 2004, 07:08 PM: Message edited by: MolaKule ]
Thank you. So as I understand it, a friction modified oil is not necessarily a better oil than one with a good base stock.
A base oil with good lubricity is better, but if one can econmically add extra friction modifiers, then that's even better.
I agree with what Molakule said - FM means different things in different lubes designed for different purposes. We have addressed engine oils. What is a good tranny oil? Well, it needs to be lubricious, the right vis for shiftability in cold climates, and also must provide proper shift "feel". This is almost entirely the result of how the synchros engage the gears - if the lube is too lubricious, the syncs will not "bite" and match their speed, causing clunk action or even a grind. Plus, especially with carbob syncs as are starting to appear, glazing can occur on the synchronizers. If they grab too much, the same result can occur. So the oils recommended have to have ideal properties. Honda used to recommend engine oil, now they have a product called MTF (manual transmission fluid), which is a 10w30 with higher amounts of ZDDP, and higher l;evels fo calcium. I believe the calcium is used more as a friction-modifier here than as a detergent orpH buffer as it would be used in an engine, since it does not have to deal with the acid byproducts of combustion. GM makes a MTF as well, called GM Syncromesh. They also make a GM S "FM, for friction modified. This was designed for a specific transmission, the NV1500 light truck tranny. My understanding is that GMS was developed because GM had started to source trannies from a number of world suppliers, including Getrag and ZF, and the ones that use yellow metals as synchronizers were suffering high warranty claims when GL-5 lubes, esp those using active sulphurs, or high levels of inactive sulphurs, were damaging the syncs. So GM spec'd its own lube, and Pennnzoil and Texaco (to name 2) make lubes specific for the GM spec. And, Red Line orf course has MTL and MT-90, which are GL-4. And guess what? - they have almost exactly the same Calcium level as Honda's MTF, with ZDDP in similar amounts. So I would expect them to have excellent shift feel in Honda trannies, and one real advantage: they will not shear down. Honda MTF look pretty played out at about 20K miles, or worse in the extra hi-revving S2000.
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